1. Field of the Technology
The present application relates generally to mobile stations operating in a wireless communication network, and more particularly to methods and apparatus for providing a tolerable delay for slotted messages in wireless networks.
2. Description of the Related Art
A wireless communication device, such as a mobile station operating in a cellular telecommunications network, may provide for both voice telephony and data communications. A mobile station may, for example, be compatible with 3rd Generation (3G) communication standards (such as IS-2000 Release 0) and utilize Global System for Mobile Communications (GSM), Time Division Multiple Access (TDMA), or Code Division Multiple Access (CDMA) wireless network technologies.
In CDMA communications defined by IS-2000, a mobile station operating in a normal slotted mode wakes up to monitor for page messages in paging slots at an interval of 1.28*2^i seconds, where i is an integer value ranging from 0 to 7. The value of i is referred to as a “Slot Cycle Index” and is chosen by the mobile station and registered with the infrastructure. Slotted messaging has been utilized in wireless communication networks for many years in an effort to conserve battery power in mobile stations.
In Release D of IS-2000, a new feature that allows mobile stations to operate in a “reduced slotted mode” while idling and monitoring for pages has been defined. Specifically, values of −4 to −1 are allowed as possible values for the Slot Cycle Index i for the reduced slotted mode. This enables faster call setup times for mobile-terminated calls. A shortened slot cycle for faster call setup is highly desirable for certain applications, such as Push-To-Talk (PTT) communication applications. The reduced slotted mode may be negotiated between the mobile station and the infrastructure at the time of call release, for example. In this case, the agreed upon value of i for the reduced slotted mode is active for a period of time before the mobile station and the infrastructure revert to the prior value of i for the normal slotted mode. Furthermore, when the mobile station is idle a new value of i can be negotiated to be active for a period of time.
Another reason that a mobile station may request to operate in the reduced slotted mode is unrelated to the need for fast call setup or PTT communications. In particular, if a mobile station is operating with a relatively high capacity or large power source (e.g. a wall power source, an automobile power source, or a PC power source through USB connection), it may request a shortened slot cycle as power savings is not a concern. The mobile station requests the reduced slot cycle in order to benefit from reduced call setup times even when another feature that requires it (e.g. PTT communications) is not active.
One problem is that, if the infrastructure has more pages queued for a particular paging channel slot than can actually fit in the slot, the infrastructure has no way to appropriately prioritize the pages. This becomes more problematic when many mobile stations in the wireless network are operating in the reduced slotted mode. Some of the pages may be destined for mobile stations having active PTT communications that require fast call setup, whereas other pages may be destined for mobile stations that do not necessarily require the fast call setup (e.g. high capacity power source use). Currently the infrastructure has no suitable technique for prioritizing pages to send within paging slots given these observations.
Other systems may exhibit similar problems. Accordingly, what are needed are improved techniques for slotted messaging in wireless communication networks.